US Patent No. 10,694,597

LED PIXEL CIRCUITS WITH PWM DIMMING


Patent No. 10,694,597
Issue Date June 23, 2020
Title Led Pixel Circuits With Pwm Dimming
Inventorship Hirofumi Watsuda, Miao-Li County (TW)
Assignee INNOLUX CORPORATION, Miao-Li County (TW)

Claim of US Patent No. 10,694,597

1. A pixel circuit for illuminating a first LED unit with a level of brightness, comprising:a first latch circuit, latching first control data according to a first latch signal to generate a first control signal;
a first pass switch, providing the first control data from a data signal to the first latch circuit according to a scan signal;
a PWM circuit, generating a PWM signal according to the first control signal and an enable signal; and
a current source, supplying a constant current flowing through the first LED unit according to the PWM signal;
wherein the first control data is divided into an MSB (Most Significant Bit) control data and an LSB (Least Significant Bit) control data;
wherein the first latch circuit comprises;
a first sub latch circuit, latching the MSB control data according to the first latch signal to generate an MSB control signal; and
a second sub latch circuit, latching the LSB control data according to the first latch signal to generate an LSB control signal;
wherein the first pass switch comprises:
a first sub switch, providing the MSB control data from the data signal to the first sub latch circuit according to the scan signal; and
a second sub switch, providing the LSB control data from the data signal to the second sub latch circuit according to the scan signal;
wherein the PWM (Pulse Width Modulation) circuit comprises:
a first sub PWM circuit, generating an MSB PWM signal according to the MSB control signal and the enable signal; and
a second sub PWM circuit, generating an LSB PWM signal according to the LSB control signal and the enable signal;
wherein the current source comprises:
a first sub current source, supplying a first current to the first LED unit according to the MSB PWM signal; and
a second sub current source, supplying a second current to the first LED unit according to the LSB PWM signal, wherein the second current is lower than the first current.